1. Field of the Invention
The present invention relates to a solid-state imaging device, a camera system, a method and a program for reading data from a solid-state imaging device.
2. Description of the Related Art
Some of image sensors such as CMOS (complementary metal oxide semiconductor) image sensors (CIS) have a resolution converting function acting primarily in the direction of scaling down for the purpose of achieving an increased frame rate through a reduction in the amount of image data to be output.
Resolution conversion is carried out using two types of approaches, i.e., thin-out and summation (or averaging which may alternatively be called binning) performed when reading pixels or performed in the analog domain and scaling which is performed in the digital domain.
“Thin-out” is a process of reading out pixels of a sensor intermittently or with some rows and columns of pixels skipped instead of reading out all pixels of the sensor, and “summation” is a process of reading out signals of a plurality of pixels simultaneously.
In addition to “thin-out” and “summation”, processes of reading out pixels of an image sensor with some of the pixels skipped instead of reading out all pixels include processes such as “slicing” that is a process of reading out part of pixels.
FIG. 1 is an illustration showing a pixel array in the Bayer format.
FIG. 2 is an illustration for explaining correction of the gravity (phase) of pixels which have been subjected to a 2×2 conversion process.
When the Bayer format is used as the output format of an image sensor, as shown in FIG. 1, the phase distances between color elements must be equal to each other.
Since the Bayer format is formed by pixel components in four colors R, Gr, Gb, and B, the above-described resolution conversion processes must be performed between pixels of the same color.
As a result of the conversion, distances between pixels of the same color are changed while distances between pixels of different colors are kept unchanged. It is therefore necessary to correct the phases of pixels to be output (the gravity of the pixels) as shown in FIG. 2.
Various proposals have been made on techniques to be used for pixel phase correction and color conversion processes (for example, see JP-A-2004-38694 and JP-A-2008-541598 (Patent Documents 1 and 2)).